To our knowledge, up to date in-vivo electrical connections were only developed for pacemaker applications. The pacing lead is connected to the pacing device with a receptacle-and-plug type connection. Reliability is often insured by using a set-screw to keep the plug in place, as described, for example, in U.S. Pat. No. 4,764,132. In these devices, non-corrosive metals, insulation, and moisture barriers are used to maintain a projected lifetime of up to 10 years. These connections are large and not hermetic. Therefore, unfavorable leakage currents can be induced during the operation of the device. These leakage currents are often mitigated through the use of insulation and distance. Leakage currents are also not as critical in pacemaker applications since the leads only carry current when the device is sending a pacing pulse.
Recently, various electro-active intraocular lens (EA-IOL) systems have been proposed. These EA-IOLs will also need electronic connections for in vivo use. However, in an EA-IOL there is no room for the large electrical connections of the pacemakers. In addition, the power supplies of these EA-IOLs are typically quite small, they are continuously operated, and all electronic modules are quite close to each other. To avoid leakage currents, and moisture ingress, followed by corrosion, in such systems, the electronic connections and the conductors between connections must be completely isolated from the in vivo environment via a hermetic interconnection scheme.
Somewhat related interconnect schemes have been proposed in the past, such as a high-density, chip-level integrated interconnect packaging system in the article “Microelectronic Packaging for Retinal Prostheses” by D. C. Rodger and Y-C. Tai, in IEEE Engineering in Medicine and Biology Magazine, p. 52, September 2005. However, the described scheme applies a polymer layer (parylene) as the hermetic coating and thus suffers from moisture ingress over time causing leakage currents and eventually, corrosion of the interconnects and connecting wires.
For at least the above reasons, hermetically sealed interconnects are needed that are small enough for implantation into an eye, essentially eliminate leakage currents even when the electronic modules are situated close to each other, and provide reliable sealing for about 10 years even when exposed to the salinity conditions of biological tissue.